There's a lot of good storylines out there that get blown to pieces by the work itself. Not doing itself justice, if that makes sense.

I don't know, I love certain ways that many romantic comedies are setup, what with the backgrounds of the characters, the locations and such... but there are an overwhelming amount of which could be done abysmally better.

Examples of anime that do put good use to good storylines include..

Kanon
Air
Clannad
Chobits
Angel Beats!
The World God Only Knows
Full Metal Panic!

I think Bleach has one of the most interesting worlds in a manga. Plus, the characters are just awesome! Although, One Piece has to be the best, in my opinion. The character development is just fantastic! Plus, Oda does a good job at keeping everything together. There are so many characters in One Piece, but every single one seems to be important! Death Note was good because it was so original. The art helped, too.